13. Abdominal Aortic Aneurysm (AAA)

Question 1

What is an aneurysm?

Answer 1

An aneurysm is defined if there is a permanent dilatation of the artery to TWICE the normal diameter.
Aortic aneurysms are classified as ABDOMINAL or THORACIC.

Question 2

What is the difference between a true and false aneurysm?

Answer 2

True aneurysm has the wall of the artery forming a capsule around the aneursym.
False aneurysm wall is made up of surrounding tissue.

Question 3

Where is the most common location for an aneurysm?

Answer 3

Infra renal abdominal artery

Question 4

What is classed as an abdominal aortic aneurysm?

Answer 4

Abdominal aneurysm is classified as an aortic diameter EXCEEDING 3 cm.

Question 5

Give 4 causes/risk factors for AAA.

Answer 5

• Most have no specific identifiable causes
• Severe atherosclerotic damage
• Family history
• Tobacco smoking
• Male
• Increasing age
• Hypertension
• COPD
• Trauma
• Hyperlipidaemia

Question 6

What is the most common cause of aortic aneurysm?

Answer 6

Atherosclerosis
Weakens the vessel wall because inflammation = release of MMPs

Question 7

Explain the pathophysiology of AAA.

Answer 7

• Degradation of the elastic lamellae.
• Resulting in leukocyte infiltrate.
• Causing enhanced proteolysis and smooth muscle cell loss.
• The dilatation affects ALL 3 LAYERS of the vascular tunic!
• If it doesn’t, then it is a pseudoaneurysm.

Question 8

How would an unruptured AAA present?

Answer 8

Often asymptomatic and only picked up via a routing abdominal
examination or plain X-ray.

• Pain in abdomen, back, loin or groin
• Pulsatile abdominal swelling

Question 9

How would a ruptured AAA present?

Answer 9

• Intermittent or continuous severe epigastric/abdominal pain, radiating to back.
• Pulsatile abdominal swelling.
• Collapse.
• Hypotension.
• Tachycardia.
• Profound anaemia.
• Sudden death.

Question 10

Describe the pain of a dissecting aortic aneurysm

Answer 10

Abrupt onset of severe, tearing central chest pain radiating through back

Question 11

Investigation for AAA.

Answer 11

1. Abdominal physical exam
   - Pulsatile mass palpated
2. Abdominal ultrasound / duplex
   - Can assess aorta to degree of 3 mm
3. CT and or MRI angiography scans

Question 12

Management of AAA.

Answer 12

Small aneurysm < 5.5 cm = monitored
1. Treat underlying causes
2. Modify risk factors e.g. smoking and diet
3. Smoking cessation
4. Vigorous BP control
- IV Lanetalol
5. Lowering of lipid in blood

Question 13

How would a ruptured AAA be repaired?

Answer 13

1. Endovascular repair with stent insertion
2. Surgical replacement of aneurysmal section